We have developed a dialysis system which is simple, safe, and portable. The BioLogic-HD system is a single access, sorbent based dialysis system with recently developed monitors to determine: total weight removal, blood flow rate, clotting of the dialyzer, and column saturation (a continually operating ammonium monitor). The ammonium contains a gas-permeable memberane which allows passage of ammonium into a pH sensitive strip. A reflectance photometer-measures color change of the strip during dialysis. We now propsed to modifiy this ammonium monitor by adding a ureas-containing strip in front of the gas-permeable membrane. The ammonium generation and color change of the monitor will be proportional to the urea level. The computers in the machince will determine the approximate blood concentration of urea by applying formulas including blood flow rate and the dialysance of the dialyzer. The machine will then be able to display: time of completion of an efficient dialysis (a 58% drop in BUN, equal to a KT/V=1), probability of saturating the Sorb column during the treatement, and comparison of chemical process to that expected for this patient (KT/V=1). The chemical results of each treatment will be used to suggest proper settings of the machine for the next dialysis of the same patient, and chemical effect of treatment will be transferred to the SmartChart(R) clinical information system. During this project, the monitor will be constructed, tested in vitro, and information transfer and interpretation algoithms completed and tested.